I. Field of Invention
The present invention relates to a new class of compounds for use as active principals for topical treatment of skin conditions, to compositions containing these compounds and to methods of treating skin conditions using these compounds and compositions. Compounds of the class include those of Formula (I): ##STR2##
wherein, R.sub.4 is (CR.sub.5 R.sub.6 --CR.sub.7 R.sub.8 --X.sub.1) .sub.n --CR.sub.9 R.sub.10 R.sub.11 ; n is an integer from 1 to 18; R.sub.1, R.sub.2, R.sub.3, R.sub.5, R.sub.6, R.sub.7, R.sub.8, R.sub.9, R.sub.10 and R.sub.11, are independently hydrogen or non-hydrogen substituents, with preferred non-hydrogen substituents including alkyls, alkenyls, oxa-alkyls, aralkyls and aryls; and X, X.sub.1, Y and Z are independently, O, NH or S, with preferred compounds including those in which X, X.sub.1, Y and Z are each oxygen and R.sub.1, R.sub.2, R.sub.3, R.sub.5, R.sub.6, R.sub.7, R.sub.8, R.sub.9, R.sub.10 and R.sub.11 are each hydrogen.
II. Description of the Prior Art
Dermal use of alpha hydroxyacids having an all carbon backbone is described in U.S. Pat. No. 5,091,171. Cosmetic compositions using 2-hydroxyalkenoic acid are disclosed, for example, in U.S. Pat. No. 5,108,751. Such compounds must have an unsubstituted alpha hydoxy group on a carbon backbone and are purportedly used in impart beneficial effects to the skin. However, the trend is away from the use of such alpha hydroxyacids since they necessitate low operational pH ranges that for the most common forms, i.e. glycolic and lactic acids, are known to cause skin irritation.
Topical formulations comprising straight, all carbon backbone, dicarboxylic acids have been proposed as replacements for alpha hydroxyacids. For example, U.S. Pat. Nos. 4,292,326, 4,386,104 and 5,385,943 describe the use of dicarboxylic acids having 7 to 13 carbon atoms for various skin indications. Similarly, U.S. Pat. No. 4,885,282 states that a 4 to 18 carbon dicarboxylic acid compound is useful for the treatment of skin disorders.
The problem with the use of these dicarboxylic acids is their inherent insolubility in aqueous solutions. Such solutions make up the majority of cosmetic delivery systems. Also, dicarboxylic acids that have all carbon backbones are solid at ambient temperatures, extremely difficult to work with and, if a solution is achieved, the result is an aesthetically unpleasant mixture unsuitable for cosmetic use.
Therefore, there is a need for a compound or class of compounds that can be used as mild, exfoliating actives for topical treatment of skin.
There is also a need for a mild, exfoliating topical composition that contains a water soluble compound that can be manufactured into an aesthetically acceptable cosmetic or dermatologic products.